Establish, if possible, a single dose carcinogenic regimen for induction of respiratory tract tumors, preferably with non-metabolized carcinogens, so that more readily interpretable studies of co-carcinogenesis or promotion can be performed for respiratory carcinogenesis. When a single dose regimen is available, study susceptibility factors, such as those which influence the rate of cell proliferation in the respiratory tract, in light of the tumor yield produced by the carcinogen. Determine whether the susceptibility of the respiratory tract to metabolized carcinogens can be influenced by chemicals known to inhibit their metabolism (e.g., Benzo(a)pyrene and 7,8-Benzflavone). Examine the effects of anticarcinogenic agents, such as vitamin A analogs, on the progression of initiated tumors into detectable and lethal tumors. Provide a bioassay resource which will be readily responsive to the need to initiate similar respiratory carcinogenesis studies.